Good questions, also important!
The source data is from the TPS model that's released every night combined with items from BPlan and the nightly CIF feeds. I've spent many months/years tagging the tiplocs to the correct locations and attach it to the track (OS/NR data). It
was crossed referenced with sources such as NESA but nothing private. I also plan to add tiploc mileages as well.
I can't share the track level detail as it wouldn't make sense without the track layout - which I can't share due to OS licensing restrictions.
In regards to licensing, I'm considering it as open and for people to use freely for whatever purpose.
Hope that answers your questions :)